Vallejo firefighters were kept busy with a three-alarm fire that engulfed a vacant building Monday night.

The fire was reported at about 7:30 p.m. at 241 Couch St.

The building, which is a closed-down army surplus store, was fully engulfed by the time firefighters arrived. Soon, a second alarm was called, calling in help from nearby cities, Battalion Fire Chief Cliff Campbell said.

The blaze was later escalated into a third-alarm because embers were seen floating to nearby structures, power lines and rail tracks. However, no other structure was damaged, Campbell added.

Vallejo firefighters are familiar with the building, since it had caught on fire twice in the past, most recently in August 2012.

Campbell said the vacant building is known to be a makeshift shelter for the homeless, and there were signs that people had been occupying the building at the time of the fire.

There were no reported injuries due to the blaze.

Power was cut briefly to the immediate neighboring buildings, but it was promptly turned back on when firefighters declared the fire under control at about 8:30 p.m.

On Tuesday, Campbell said the fire was suspicious in nature, and is under ongoing investigation.

While they were battling the flames on Couch Street, a small Dumpster fire was reported in the 500 block of Benicia Road. No other information was available on it.